While there are numerous exercise activities that one may participate in, exercise may be broadly broken into the categories of aerobic exercise and anaerobic exercise. Aerobic exercise generally refers to activities that substantially increase the heart rate and respiration of the exerciser for an extended period of time. This type of exercise is generally directed to enhancing cardiovascular performance. Such exercise usually includes low or moderate resistance to the movement of the individual. For example, aerobic exercise includes activities such as walking, running, jogging, swimming or bicycling for extended distances and extended periods of time.
Anaerobic exercise generally refers to exercise that strengthens skeletal muscles and usually involves the flexing or contraction of targeted muscles through significant exertion during a relatively short period of time and/or through a relatively small number of repetitions. For example, anaerobic exercise includes activities such as weight training, push-ups, sit-ups, pull-ups, or a series of short sprints.
To build skeletal muscle, a muscle group is contracted against resistance. The contraction of some muscle groups produces a pushing motion, while the contraction of other muscle groups produces a pulling motion. A cable machine is a popular piece of exercise equipment for building those muscle groups that produce pulling motions. A cable machine often includes a cable with a handle connected to a first end and a resistance mechanism connected to a second end. Generally, the resistance mechanism is an selectable set of weights. A midsection of the cable is supported with at least one pulley. To move the cable, a user pulls on the handle with a force sufficient to overcome the force of the resistance mechanism. As the cable moves, the pulley or pulleys direct the movement of the cable and carry a portion of the resistance mechanism's load.
One type of cable exercise machine is disclosed in U.S. Patent Publication No. 2002/0025888 issued to Kyle M. Germanton. In this reference, an exercise machine has an automatic and programmable resistance selection apparatus with vertically aligned weights that are selectable by rotably engaging a lift pin to select each weight stack. The exercise machine further includes a control module from which the number of weights to be lifted can be ordered by the user. Alternatively, the number of weights being lifted may be programmed from a remote location. Other types of cable exercise machines are described in U.S. Pat. No. 7,473,211 issued to Byung-don Lee and U.S. Pat. No. 6,117,049 issued to John C. Lowe.